Measuring gelatinase activity in colorectal cancer

Aims: Gelatinases (MMP-2, -9) are the most extensively studied MMPs in cancer. The aim of the study was to determine the levels of active and latent forms of the gelatinases in paired colorectal tumour and normal tissue (n =77) and correlate these with pathological stage. Methods: Gelatinase levels were compared following the techniques of gelatin zymography (active and latent) and the novel gelatinase activity assays (total and endogenous/active). Results: Both latent and active MMP-2 and MMP-9 lysis bands (zymography) and both total (active and latent) MMP-9 and endogenous (active) MMP-9 and MMP-2 levels (activity assays) were greater in tumour than normal colorectal tissue. Total MMP-2 and MMP-9 levels as determined by activity assays correlated with both the Dukes staging (e.g. total MMP-9 in tumours: adenoma, 1.0 (0.3–3.6); Dukes A, 9.6 (2.4–35.4); Dukes B, 14.7 (1.5–103.9); Dukes C, 22.3 (2.2–57.9) and Dukes D, 37.4 (2.1–47.0) ng/mg protein) and with lymphatic invasion (e.g. total MMP-9; in tumours which had undergone lymphatic invasion, 22.7 (2.1–57.9) and those with no lymphatic invasion, 14.0 (1.5–103.9) ng/mg protein). Conclusions: Both gelatinases were upregulated in tumour tissue, however total and not endogenous active levels correlated with the pathological stage of the tumour. Therefore gelatinases may only be activated when required for tumour invasion and metastasis.